If somebody were to ask you to prove that you are alive, what would you do? You would run and jump and scream and shout "I'm alive!" And the evidence would be irrefutable.
And the person would respond.
"You are alive outside, but are you alive inside?"
And you would show the things you love and care about. You would show the things you've built and accomplished and collected. You would share your vision of your future. And the person would then agree that you are alive.